The camera has several methods of recording, including SxS cards, CFast 2.0 cards and SXR Capture Drives at resolutions up to 2880 x 2160 pixels in either Rec. 709 or Log-C to ProRes or ARRIRAW codecs. Alexa camera owners can purchase additional software licenses that will unlock different capabilities of the Alexa Camera including High Speed 120fps recording, DNxHD codec and 4:3 "Open Gate" Mode for anamorphic lenses.

The first camera of the Alexa product family. The ARRI ALEXA’s CMOS Super-35mm sensor is rated at 2.8K and ISO 800. That sensitivity allows the camera to see a full seven stops of over exposure and another seven stops of underexposure, an unprecedented Dynamic Range. To take advantage of this, ARRI offers both industry-standard REC709 HD video output as well as the Log-C mode that shows the entire range of the chip’s sensitivity, allowing for an extreme range of color correction options in post.

The ALEXA Plus added integrated wireless remote control, the ARRI Lens Data System (LDS), additional outputs, lens synchronization for 3D, and built-in position and motion sensors and a 4:3 sensor making it ideal for anamorphic cinematography.

In February 2013,[2] the range was renewed as Alexa XT (XT standing for extended technology). This range is upgraded versions of the original Alexa cameras, which are equipped with a so-called XR module, which replaces the SxS module on the cameras, and allows direct RAW recording without the need for an external recorder. This module records on dedicated SSD drives. Further improvements are an internal ND filter unit, a 4:3 sensor and a quieter cooling fan. The range accordingly comprises the Alexa, the Alexa XT, the Alexa XT M, the Alexa XT Plus, the Alexa XT Studio, and the Alexa Fiber Remote. Existing cameras can be upgraded with the XR module for internal RAW recording.[3]

On 21 September 2014 at the Cinec convention in Munich, Arri announced the Alexa 65,[4] a 6k 65mm digital cinema camera. As with cameras from competitor Panavision, the Alexa 65 camera was available by rental only, provided through the ARRI Rental Group.[5] The Alexa 65 uses the A3X sensor, which has a maximum recordable resolution of 6560x3100.[6][7]

On 18 March 2015, Arri announced the SXT line of Arri Alexa cameras which will support in-camera upscaling of Apple ProRes to 4K resolution and Rec. 2020 color space.[11][12] Arri also announced the SXR module which can upgrade XT, XT Plus, and XT Studio cameras with the SXT features.[11][12]

The Alexa's ALEV III sensor has 3392×2200 effective pixels used for generating an image, 2880×2160 pixels are generally used for recording on the Alexa Studio and M in 4:3 mode, and 2880×1620 pixels are used for recording on the regular Alexa and other models in 16:9 mode, the rest of sensor is used for lookaround in the viewfinder. Alternately the full sensor resolution may be employed in 'Open Gate' mode for resolution demanding situations.

Director Robert Tur with an Alexa-Plus camera equipped with an 18 mm Master Prime lens on the set of SIS.

The Alexa 65 uses the A3X sensor, which has a 54.12 mm x 25.59 mm active imaging area. It provides up to 6560x3102 'Open Gate' maximum recordable resolution, and is bigger than traditional 65mm film.[7]

The Arri Alexa can record to 1920×1080 ProRes 422 or ProRes 4444 on SxS Cards or 2880×1620 ARRIRAW to external recording devices. The Arri Alexa Firmware 7 increases the resolution on the SxS cards to 2k ProRes 4444 (previously 1080p)

ArriRaw is a raw codec similar to CinemaDNG that contains unaltered Bayer sensor information, the data stream from the camera can be recorded via T-link with certified recorders like those from Codex Digital or Cineflow.

The ArriRaw format (along with the other recordable formats) contains static and dynamic metadata. These are stored in the header of the file and can be extracted with the free web tool metavisor[13] or with the application Meta Extract provided by Arri. Of particular importance for visual effects are the lens metadata, which are stored only when Arri's lens data system (LDS) is supported by the lens used.